The present invention relates to a high frequency treatment tool, which is provided with a needle-shaped high frequency electrode configured to project forward and recede from a distal end of a sheath to be inserted into and pulled out of an accessory channel of an endoscope.
A high frequency treatment tool for an endoscope, which is used to give treatments of incision/coagulation for body tissues such as mucous tissues, is preferred to be configured to rinse out the surface of the mucous tissues as an object of such treatments before incision of the surface and rinse off cauterized pieces of the mucous tissues, which are burnt to adhere to an electrode and/or its neighboring portions, during the incision.
For this reason, a high frequency treatment tool for an endoscope has been developed, which includes a high frequency electrode provided in an electric insulating sheath to be inserted into and pulled out of an accessory channel of the endoscope, the high frequency electrode being configured to project forward and recede from a distal end of the sheath according to an operation at an operator's hand side of the sheath. In addition, the high frequency treatment tool is configured such that space surrounding the high frequency electrode (and an operating wire coupled with the high frequency electrode) is employed as a water channel through which water to be squirted out of the distal end of the sheath is conveyed. Such a high frequency treatment tool, for example, is disclosed in Japanese Unexamined Patent Publication No. HEI6-292685.
However, when the space surrounding the high frequency electrode is employed as a water channel, the delivered water amounts and/or water flow conditions are quite different between both states of the high frequency electrode projecting and receding from the sheath. Therefore, such a high frequency treatment tool is hard to use.
A high frequency treatment tool, in which there are separately provided a wire insertion channel through which an operating wire is inserted and a water channel in parallel with one another, is considered as a solution to overcome the above problem. However, in such a high frequency treatment tool, when a high frequency electrode is arranged on an axis line of a sheath, a cross-sectional area of the water channel is restricted to be small. On the other hand, when the high frequency electrode is not located on the axis line of the sheath, it is likely to be hard to use because it is difficult to grasp the location of the needle-shaped high frequency electrode during the incision operation.
Further, in such a high frequency treatment tool, since water squirted out of a distal end of the water channel does not reach a tip of the high frequency electrode, it is impossible to efficiently rinse off the cauterized pieces of the mucous tissues, which are generated around the high frequency electrode during the incision operation. Thereby, the incision operation may be cumbersome.